And yes also remove cookies sometimes virus comes into the computer due to that.

Delete any undeletable virus/file

1.Open Notepad.exe
2.Click File>Save As..>
3.locate the folder where ur undeletable file is
4.Choose ‘All files’ from the file type box
5.click once on the file u wanna delete so its name appears in the ‘filename’ box
put a ” at the start and end of the filename
(the filename should have the extension of the undeletable file so it will overwrite it)
click save,
6.It should ask u to overwrite the existing file, choose yes and u can delete it as normal